Memory devices have a wide range of uses in modern electronics and electronic devices. In general, various types of electronic memory exist, including hard disc memory, floppy disc memory, magnetic tape memory, optical disk memory, and so on. One of the more innovative and diversified types of memory is semiconductor memory.
One type of semiconductor memory commonly used for modern electronics is nonvolatile Flash memory. Flash memory comprises arrays of semiconductor devices that can be utilized to store, erase and re-store digital information. Compared to other types of electronic memory, Flash memory is fast both in terms of programming and erasing, as well as reading data, has good data retention characteristics, and is highly cost effective. Accordingly, Flash memory is utilized for data storage in an ever-increasing number of electronic devices and applications, including computers, cell phones, smart-phones, digital cameras and camcorders, game stations, and so forth.
One great advantage of Flash memory is that stored data can be retained without continuous electrical power applied to a Flash memory module. In addition, Flash memory is a solid-state technology that can be very dense—in terms of memory cells per unit volume—typically requiring no moving parts for basic operation. Accordingly, Flash memory is ideal as removable and portable data storage for consumer electronics, and is utilized with universal interface technologies for a wide array of electronic devices, such as universal serial bus (USB) technology.
Like most consumer electronic technologies, advancements in nonvolatile memory are driven by a desire for faster, more dense (in terms of data storage per volume) and more cost-effective electronic devices. One major limiting factor for speed and sophistication of electronic devices and complexity of device software is the physical capabilities of digital memory employed by those devices. Invariably, smaller, faster computers require faster and denser memory. Research and development in nonvolatile memory is therefore generally focused on achieving these goals. In recent years, this research and development has achieved many advancements in nonvolatile solid-state memory, providing faster program, erase or read times, reduced power consumption, greater memory density, increased storage reliability, reduced error rate, and the like. However, these advancements are not all achieved in unison, and can be particular to different types of solid-state memory. For instance, in regard to Flash memory, NAND-type semiconductor memory has among the best program and erase speeds, and is highly scalable with higher cell densities, but has a relatively slow read times and long-term storage reliability. On the other hand, a NOR-type semiconductor provides much greater read speed than the NAND-type semiconductor, and has better long-term storage reliability. These memory technologies (and other nonvolatile memory) have different semiconductor structures, however, so achieving the benefits of both semiconductor types is not a simple task. Ongoing research in non-volatile memory is directed at improving upon these memory technologies, however.